The objective of this project is to provide a firm biochemical basis for understanding the mechanism involved in hemostasis and thrombosis. Attempts will be made to isolate and characterize (a) fibrinogen, (b) fibrin-stabilizing factor, (c) anti-fibrinolysin, and (d) thrombosthenin of blood platelets. The physical and chemical properties of these proteins will be compared with their plasma counterparts. These studies will then be extended to patients with abnormal platelet function.